Distribution and Intensity of the Built-in Field in Poled Silica Thermally Based on a Junction Model

Formation of depletion region and the charge distribution are analyzed using multi-charges’ migration under a polling field in fused silica. The internal fields induced are calculated based on a junction model. The field distributions and their intensities within the whole depletion inside the silica are calculated. The maximum field is on the order of 109 V/m in a abrupt junction, and the optical nonlinearities generated by this internal field are consistent with the experimental results published, which proves the junction model is reasonable and feasible to calculate optical nonlinearity in air by thermal polling.

Normally-Off 4H-SiC Vertical JFET with Large Current Density

We developed normally-off 4H-SiC vertical junction field effect transistors (JFETs) with large current density. The effect of forming an abrupt junction between the gate and the channel was simulated, and vertical JFETs were then fabricated with abrupt junctions. As a result, a large rated drain current density (500 A/cm2) and a low specific on-resistance (2.0 mWcm2) were achieved for small devices. The blocking voltage was 600 V. These results were due to a reduction of the threshold voltage by forming the abrupt junction between the gate and the channel.

Thermal Interface Resistances in Nanostructures

Nanostructured electronic and photonic devices include a high density of material interfaces, which can strongly impede heat conduction and influence performance and reliability. Thermal conduction through interfaces is a very mature field as long as the interface dimensions are large compared to the phonon wavelength. In nanostructures, however, the confinement of phonons in the directions parallel to the interface may strongly influence heat conduction. The present work investigates a model problem consisting of an abrupt junction between a harmonic 1D and 2D square lattice. The results show that energy couples to phonon modes localized near the free surface and that the energy transmission coefficient across the interface into these surface modes is less than unity even for materials with identical bulk impedances. The lattice dynamics calculations performed here provide an initial perspective on the impact of phonon confinement on the acoustic mismatch resistance and lay the groundwork for more detailed studies involving 3D molecular dynamics.